Science of Fear
by itsirmster
Summary: This was a prompt from tumblr user @im-on-your-side-now. Cosima's health fails and Sarah has to take her place at the DYAD, leaving Delphine conflicted in more ways than one.
1. Chapter 1

"Oi! Watch it!" Sarah snapped at Felix, yanking her head to the side and causing herself more pain. "Jesus bloody Christ." Cursing under her breath and her teeth gritting at the pain, Sarah reached out for her hair and rubbed her scalp.

"Sarah!" Felix scolded exasperatedly, throwing his arms up in the air. "You're screwing it all up. Would you just let me finish? Please?" His hands reached out for her hair cautiously again, and Sarah slouched back in the chair.

The two spectators that were sitting on the couch both had amused grin on their faces.

"Was it like this when you were getting your dreads, cherie?" Delphine murmured through her giggle before she turned to Cosima.

Despite the light mood all four of them were in, the immunologist felt her heart sink a little.

Yes, the Darwinist was laughing, but her laugh was almost always interrupted with coughs that shook all her petite body. Her eyes were still smiling under the dark-rimmed glasses but were now also decorated with two dark circles around them, contrasting eerily with her pale, almost transparent skin. When she coughed, her hand brought a tissue to her lips, sighing upon seeing blood on it and her thin arm trembled as she lowered it down.

Catching Delphine's gaze, Cosima smiled at her just as brightly, all the same fixing the IV that was attached to her arm. Automatically, Delphine's hand covered hers, giving her a light squeeze.

"Actually, Delphine," Her voice was hoarse but still playful, "This is the first time I see myself more of a badass than Sarah. And those aren't, like, even real dreads." Her hollow cheeks filled with air as she laughed again. Sarah was the only not amused one, and her eyes rolled.

"Just get it over with, Fe. We don't have too much of a bloody time, now do we?"

/

"Are you okay?" The blonde's voice was merely a whisper and a brow slightly furrowed as she adjusted the pillow under Cosima's head.

"Yeah, yeah, of course. Don't worry about me." Cosima replied, mustering yet another smile before she coughed in her tissue again. These days she could only sit up long enough to eat or walk to the bathroom before she would feel drained again.

The DYAD was the only option left, to everyone's disappointment, but all of it needed to be done in secrecy. Leekie was not to know about Cosima's illness, not yet, which was the reason Sarah had her hair pulled out in order to make believable dreadlocks, combined with a wig Felix had found.

"You know I worry." Delphine replied, her hand stroking Cosima's temple gently. She wished that for just one more day she could see her Cosima being full of life, with filled cheeks and a non-sickly tan. She wished that for one more day they could take a walk in the park or drink wine bottles on the campus. But that day _would _come. It had to.

The look they exchanged, the silent look that was appearing more often as of late, and that said more than any words could, was interrupted by the voices that came out of the bathroom where Sarah went to finish up the last touches of her new 'science geek' look, as Felix dubbed it.

"You make a better Cosima than Alison, I gotta give you that." Felix said, his arms crossed on his chest, face swelling with pride at his own work.

"Shut up." Sarah snapped, fixing the glasses up her nose and shrugging her shoulders, her weight shifting on one leg as Cosima used to do.

Delphine turned around and a comment got hitched in her throat at the sight of Sarah. Only it was not Sarah anymore. With the dreads tied up in a bun, the mouth twitching the same way Cosima's did, and hands shoved inside the pockets of the red coat she loved so much, it seemed like that the ghost of the Christmas past had taken her back to the time when they had just met.

Her heart suddenly beat a little bit faster, and it seemed that moment in which she had stopped breathing had lasted for a small lifetime.

"Dude." The real Cosima's voice behind her snapped the blonde out of the small trance she had fallen in. "You're spot on." Cough. "You can totally pass as me. Look at Delphine, she's like, speechless." Another chuckle. And another cough.

"You can look but you can't touch, Frenchie. Yeah? Let's go." Sarah barked, breaking the illusion and causing Delphine to get up from the bed and finished buttoning up her own coat. Her gaze lingered on Sarah for couple of moments before she looked at Cosima, whose eyes were closed after she had taken off her glasses to give them to Sarah. Her lips moved, as though she could feel Delphine's gaze on her face.

"Take care of yourself, 'kay? Don't let Sarah punch Leekie in the face or something."

Delphine laughed, lowering herself to place her lips on Cosima's hot forehead, and then on her lips. She had fever again.

"We will be back soon. Sleep the fever off, yes? Je t'aime." Her hand stroke the dreads and their eyes met once Cosima opened hers.

"I love you too. Good luck."

/

"We're very pleased to have you here, Cosima."

Leekie had a wide smile on his face, one of those that Delphine had grown to admire over so many years, and now despised with every core of her being. Each time he would smile at Sarah, her own hand gripped the wine glass a little bit tighter, threatening to break it.

"I understand that this is an opportunity of a lifetime. Delphine made the decision easier. You're all great at what you do, and I'd be an idiot to miss the opportunity."

Delphine's gaze fell on Sarah, trying to keep her face straight. How was it possible that every single detail of Cosima's appearance, including the way she waved her hands and held herself while smiling at Aldous Leekie, was spot on? Even the accent and the low husk that only Cosima out of all the other clones had, was close to perfect.

"We're glad that Delphine made you change your mind. You're a valuable asset to the DYAD and the neolutionist movement as a whole. We're happy to have a Darwinist as talented as you are on our team."

_Bullshit. _Delphine thought.

"And I am personally glad that you and Delphine found a common… tongue." He added, and the blonde could see Sarah's face twitching a little bit.

Even though he had a smile on his face, Delphine could hear the snide remark hidden behind it. It had all started when he read Delphine's emails to Cosima, since the DYAD employees had no privacy whatsoever, which she found out about way too late in the game. Since then, she always had to listen to him commenting on their relationship and keeping an even closer eye on her. It was a nightmare. The only remotely good thing that came out of it was the fact that she did not sleep with him anymore, as he had told her he was disgusted by her poor choices.

Barely holding back an eyeroll, Delphine took a sip from her glass and watched the rest of the conversation unfold before Leekie left them both alone.

The welcoming party for the new couple of DYAD employees was a great event, and everyone was going out of their way to have a talk with the 'great mastermind' Aldous Leekie. Sarah and Delphine moved to the side as soon as he left them alone, feeling relieved that everything went according to their plan.

"You were very good." Delphine praised Sarah, who had finally dropped the grin from her face and scowled, the way only she knew how to.

"Yeah, yeah. It took everything not to bloody break this glass and shove it in his face."

"Shh," Delphine shushed her, but a giggle left her lips. Even though she had met Sarah properly only the month before, and she was a lot to handle, the two of them found a common trait, which was to protect Cosima at all costs. "Do not let them hear you."

"Let them hear me. I'll bloody kill them all from keeping Kira away from me. You said Rachel would be here, Delphine."

"She should have." Delphine looked around. "Maybe later. Oh merde."

A photographer was rushing their way and Delphine immediately knew that Leekie had sent him, judging by the look he was giving them from across the room.

"A photo of the brilliant couple?" The guy suggested, and the immunologist saw Sarah's mouth fell open a little.

He wanted a scene, and a scene he would get.

"I am so sorry." Delphine whispered, and before Sarah could understand what was happening, or protest for that matter, the blonde cupped her cheeks and brought her up for a kiss.

Sarah's lips were much rougher than Cosima's, and the scent was completely different, but then again, Delphine did not feel the taste of blood in the kiss for the first time in a long time. The mixture of emotions were further confusing when they pulled away and she saw those hazel eyes and rimmed glasses. It only lasted for part of a second, for Sarah's scowl returned as soon as the photographer walked away after several shots.

"What the hell, Delphine? We agreed no bloody PDA!" She hissed under her breath, sipping the wine as to wash away what just happened. Delphine, on the other hand, looked content.

"Leekie was watching. He is not anymore." The two looked his way, and then back at each other.

"I'm a better kisser, aren't I?" Sarah asked with a smirk and raised eyebrows, and Delphine could not help herself, and laughed.

Then the phone buzzed in her pocket.

"It is from Felix." Her face, lit up only second before, turned to a frown, and then to worry. "I have five voicemails, Sar- Cosima."

The sinking feeling was back again. They had told him not to call unless it was a great emergency. Sarah pulled her own phone from the pocket, and saw that there were four voicemails there. And a text message.

"Shit, Delphine." Sarah said, lifting her gaze from her phone.

"What… what?" Delphine could feel herself panicking now. She wanted to shout: It is not Cosima, Cosima is okay, nothing is wrong-

"Her heart stopped. Fe called an ambulance. They're in the hospital."

"We need to go." Delphine said, only a bit relieved. _She was alive. She was going to be okay. They are going to be okay._

"What about the bloody party?" Sarah asked, but Delphine was already passing her the coat.

"We will say we will be back later. Come on."


	2. Chapter 2

/

"Yeah yeah, I'm her twin sister."

The nurse was eyeing Sarah suspiciously over Cosima's chart, and Delphine was standing right behind her, hugging herself protectively.

_I need to see Cosima. I need to know that she is okay._

She bit her bottom lip and turned her head around nervously before her eyes fell on the nurse again. Sarah was fuming next to her.

"Look, you can take my blood and prove that we're sisters, yeah? Look at my bloody face, it's the same."

The nurse did nothing but raise her eyebrows, and then finally lowered the chart.

"Fine. Is it only the two of you?"

"Yes." Delphine said, the weight in her chest threatening to bust her ribcage open if she was to wait for another minute without seeing for herself that Cosima was breathing.

"I'll make an exception since it's past visiting hours just this once. There can't be more than one person in the room. Miss Niehaus can't suffer from any excitements right now, the polyps on her lungs and various infections had weakened her heart. We need to be very gentle with her and wait if she responds to the medication. The doctor will see you in the morning."

It took all of willpower for Delphine to keep a steady pace with Sarah once they got the room number, fighting the urge not to break into a run. Leekie's stare was still embedded in her brain, but the immunologist could not care less. Cosima was the only one she had her eyes for. Cosima needed to be alright.

The two of them entered the room as calmly as they could so as to not disturb her. Felix was sitting in the chair, his eyes looking up at the duo before he got up.

Delphine barely noticed him, though. Her eyes fell on Cosima, who was lying there, still as death, her tiny body seemingly shrunken under the hospital covers and set of three pillows. The breathing apparatus was connected to her, together with the IV, and she was whiter than both the sheets and walls combined.

"Oh, Cosima." She whispered, and Felix came to stand by Sarah, who was standing stone still, wishing that she could do something, yet knowing that she could not. That acknowledgement alone made her want to go on a rampage. Yet, she could not move, not even when Felix put his hand on her forearm, suggesting that they should give the pair some privacy.

Delphine did not notice when the two of them eventually made a quiet exit. All of her senses were concentrated on ragged breath and wheezing she heard coming through Cosima's slightly lopsided mouth. Her lips, the lips she adored to kiss so much even when they tasted of blood, were cracked and as pale as the rest of the skin, so pale that one could not see where the lips finished and the skin started.

"I am so sorry I left you, my darling." Delphine murmured, her eyes welling with tears as she caressed Cosima's jaw. The steady ticking of the heart monitor brought little comfort, for that was the only sound in the room.

Delphine wanted to listen to Cosima's voice, no matter how weak. She wanted to see those hazel eyes looking at her disapprovingly for tears were streaming down her face silently, and she did not even bother to stop them. Yet, there was nothing but silence. Silence, and the heartbeat she loved to listen to deep in the night, when her head used to lie on Cosima's chest and their naked bodies tangled into each other.

Those nights seemed to be a lifetime ago.

_Please wake up, Cosima. I am never leaving you again._

/

"How the hell did this happen, Fe?" Sarah paced few steps, her fingers about to run through her hair when she realized that it was tied back into improvised dreads. It dropped to her side, and she gritted her teeth instead, exhaling through her nose. "She was bloody fine when we left-"

"Sarah." Felix said, glancing over at the clock. It was five minutes past midnight. He tried to calm his sister down, all the while thinking that their trips to hospitals seemed never ending. The thought of Sarah lying in there one day, since the disease seemed to be infecting all of them, one by one, made him choked up. He shrugged it away, knowing that at least he needed to keep his head clear.

"Let's sit down. Yeah?" He led her to the set of chairs in the empty hall. There were no sounds in the hospital, but the steady clock ticking, as if counting down to the moment they were all dreading. As if mocking them.

Tick tock, tick tock.

When Sarah buried her face in her hands, previously having taken off Cosima's glasses with such care as if she had the Darwinist herself in her hands, and placed it on the table next to the chair she was sitting on, Felix thought it was safe to start talking.

"It was all good for two hour after you two left. We even played poker and she seemed lively after the fever lowered down after she got the meds Delphine left. Then I went to shower, and right before I stepped in, I heard her calling me. I ran, and saw that she was paler than this wall, Sarah. It was awful. She looked like Beth Childs in that morgue. Terrifying."

Sarah looked up, giving him a look that made him shut up about Beth and continue with the story.

"I called the ambulance right away, I wasted no time. They told me I called just in time. She was almost dead, Sarah. I thought she would die on the way to the hospital. I called you two from the ambulance but you weren't picking up. And then you called, as soon as they brought her to this room."

Sarah's was tapping her foot nervously on the floor, her fingers entwined together and on her forehead, elbows on her knees.

"God dammit, Felix. We are so close. She can't bloody die on us now."

"She won't die." But even he did not believe his words.

Both of them looked up when the door slid open and Delphine appeared. Her eyes were red and puffy, but the tears have stopped pouring out.

"Cosima is… she's awake." She mustered a small smile, but her arms were still around her, as if shielding herself. The look of Sarah with dreads and the red coat only made the pang in her chest hurt more.

"She wants to see you, Sarah."

/

"You need to promise me." Her voice was barely audible. Every word she spoke out was like another knife in her lungs.

"Bollocks, Cos. You're not going anywhere. You hear me? You're the one who'll be taking care of her. Not me."

A small smile played on the Darwinist's lips as she moved her eyes to the side towards the glass of water. Sarah fetched it right away, and helped her take a sip.

"Just promise me. Delphine has no one. She turned her back on her DYAD family. She will have only you when I'm… when I'm…"

She did not need to finish the sentence. Sarah knew exactly what she wanted to say, and was still denying it with a stony look on her face, but deep inside she knew.

"Alright. Alright. But I also promise to kick your arse once you're out of the hospital. Yeah?" Her lips attempted a smile, but her features seemed too frozen for that expression. Cosima did smile though, a smile that broke Sarah's heart.

"Deal." She whispered, closing her eyes again, and giving Sarah's hand a light squeeze. Sarah reciprocated, but not too tightly, afraid that she might break her bones.

/

"I will stay with her tonight. You can go sleep." Delphine said, even though dark circles around her eyes indicated that she needed sleep too, but she fought it with her fourth cup of coffee. It was three a.m.

"I'll stay too. You go home Sarah, maybe Art will call you on the lead. Yeah? At least one of us needs to have an hour of a shuteye."

Even though Sarah wanted to argue with them, she could feel every bone in her body aching. The past several weeks were catching up to her. Finding Kira was yet another priority, and there was still the act they needed to play with the DYAD.

"You better call me at 6 a.m. I will come here with new clothes and breakfast."

"Okay." Delphine said, smiling at Sarah, at which Sarah's lip twisted into a smallest of smiles.

"I'll be back soon. See you in a few hours."

As she waved them goodbye, and peeked at Cosima through the door, little did she know that they would be seeing each other a lot sooner.

/

The heavy metal door of Felix's loft slid open and woke Sarah up with a start. She had all of her clothes on still, except from the boots and the coat, since she was too tired to get rid of the dreads or the dress. Her eyeliner was still intact, as she passed out on the couch as soon as her back hit the cushions.

Her eyes immediately flew to the windows. It was still dark outside.

"Wha -"

The sound of the door sliding shut averted her attention to the newcomer, and her heart stopped for a second when she saw Delphine.

The blonde's expression was too hard to read, and Sarah was still not completely awake to decipher anything from her face. "Delphine? What are you doing here? What time is it?"

She rubbed her temples and watched the French woman stand leaned on the metal door, unmoving, not talking, yet with her eyes glued on Sarah as if she was seeing a ghost.

"Oi!" Sarah voice was a little sharp, but it was more the terror that made her snap, than anything else.

"It's five-thirty." Delphine finally said, yet made no effort to move.

Sarah stood up slowly, her eyes finally getting used to the dim light of the early dawn.

"Delphine?" She tried again. "Why are you here? Where's Fe?"

The immunologist looked like Sarah had slapped her in the face. She looked disoriented for a split second longer, and then she burst into tears, her hand lifting to her face as if to hide it.

"It's Cosima. She's… she's…"

Sarah felt like screaming. Delphine did not need to finish the sentence. That sentence was hovering over all of their heads for months now, but tonight it was more apparent than ever before. Even after she had left the hospital, a part of Sarah knew that the conversation she had with Cosima about taking care of Delphine was their last one. Maybe that was why she delayed leaving her bed. Maybe that was why she placed her lips on Cosima's forehead, something she had never done before.

Yet, she did not cry. She did not yell. Instead, she turned on her heel and went to make them a cup of tea, each step she took making her insides twist a little more.

/

The two of them sat in silence until the sun came up. Sarah did not know where Felix was, and somehow forgot to ask.

"Sarah?" Delphine's voice was surprisingly soft once she finally spoke, and the brunette looked up from the cup with the tea that had grown cold in her hands.

"What?" The tiredness had washed over her whole, and she knew that it was for the best. Had it not, she would have probably gone off to do something rash.

_It's the time to resist our predisposition to impulsive behavior, Sarah._

The words that Cosima told her once were now echoing in her head. She could hear it in her ears. Cosima's voice, or the memory of her voice was the only thing that kept her collected.

"Can I… hug you?" The words sounded weird and they echoed strangely through the empty loft and between them, now that they were sitting on the bed, the bed that Cosima occupied less than twelve hours previously, and laughed at Sarah's transformation.

Without words, Sarah put the cup on the bedside table and motioned Delphine to come closer.

The hug lasted painfully long, or painfully short, neither of them could say. Delphine could have sworn that she fell asleep on Sarah's shoulder, for when she snapped out of it and the two of them broke apart, yet keeping close, there was a flash of Cosima in Sarah's eyes, and the dreads were not helping any.

Before Delphine knew it, her lips were on Sarah's, even though she immediately knew that she was not Cosima. Cosima was gone, and was not coming back.

"What the hell are you doing!?"

"I am sorry, oh god I am so sorry I do not know why I did it…" The tears were once again streaming down Delphine's cheeks, and her hands covered her face as she sobbed into them.

_Take care of her for me, Sarah. _

The silence that pressed both of their ears and broken by Delphine's sobs every now and then was excruciating.

_Promise me you will._

"Hey." The brunette finally spoke, her hand reluctantly placing itself on Delphine's knee.

"I do not know what has gotten into me Sarah I'm so so…"

"If you apologize one more time I am going to kick you from the bed and make you sleep on the couch. Yeah?" Sarah's eyebrows raised, and she attempted a smile, yet failed again.

Delphine smiled weakly, wiping away her tears with her thumb and nodding, sobs hitching in her chest.

"I will not sleep. I cannot sleep. And we need to arrange funeral and…" Everything that had been on her mind, or at least should have been on her mind was now pouring out of her. Her fingers got tangled in her blonde locks and she gripped them.

"Lie on my lap." Sarah blurted out, interrupting Delphine mid-babble that she was not really listening to. She still had Cosima's voice ringing in her ears.

"Quoi?" Delphine was so surprised by Sarah's words that her eyes widened and her hand lowered down.

"Lie on my lap. I know that's how you and Cosima slept, isn't it? Just lie on my bloody lap and sleep for fifteen minutes. We have a lot of shit to do in couple of hours."

Delphine looked at Sarah, her eyes seeing through her. They have looked so similar in the same clothes and with the same hair, minus the glasses and the accent, yet they were so different. Something in Sarah's determined voice made Delphine's heart hurt just a little less. In Sarah's eyes she saw Sarah, yet she also saw something that Cosima had left behind, but she was not sure what it was. Not yet.

Letting out a shaky breath, the blonde put her head down in Sarah's lap, keeping herself in fetal position and feeling tears welling in her eyes again. The fabric of the dress under her cheek smelled of Cosima, and the hand that placed itself on her head felt like Cosima's at first.

"Thank you, Sarah." She muttered, closing her eyes and feeling a heavy sleep overcoming her completely.

Sarah, on the other hand, was more awake than ever. _The things I do for you, Cos. _She smiled at nothing in particular and turned her head towards the bright blue sky of the early spring day.

_What will we ever do without you?_


End file.
